Répartition des ressources et changements saisonniers de l'alimentation d'ombles de fontaine anadromes, Salvelinus fontinalis

1982 ◽  
Vol 60 (12) ◽  
pp. 3068-3070 ◽  
Author(s):  
Alain Gaudreault ◽  
Martin Castonguay ◽  
Gérard J. FitzGerald
Keyword(s):  
Resource Partitioning ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Prey Type ◽  
Brook Charr ◽  
Lower Estuary ◽  
First Time ◽  
Winter Feeding

Resource partitioning among anadromous brook charr in an estuary included habitat and prey-type partitioning. In spring and summer, juveniles were foraging in the upper estuary on crustacea and insects while adults were eating crustacea and fish in the lower estuary. In the fall, adult charr, which were all in the river, ate little. During winter, adult charr were found in the estuary and consumed crustacea and only a few fish. The relative weights of stomach contents were similar in summer and winter, showing for the first time the importance of winter feeding for this species.

A survey of the parasites of nonanadromous and anadromous brook charr (Salvelinus fontinalis) in the Tabusintac River, New Brunswick, Canada

1987 ◽  
Vol 65 (6) ◽  
pp. 1354-1362 ◽  
Author(s):  
Jack P. Frimeth
Keyword(s):  
New Brunswick ◽  
Salvelinus Fontinalis ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
The Arctic ◽  
Brook Charr ◽  
New Host ◽  
Marine Parasites ◽  
First Time ◽  
Hysterothylacium Aduncum

A parasite survey of 1146 brook charr (Salvelinus fontinalis) was conducted between January 1981 and December 1982 in the Tabusintac River, New Brunswick, Canada. A total of 36 parasite species were recovered, of which 18 (one Myxosporea, two Monogenea, three Digenea, three Cestoidea, five Nematoda, one Acanthocephala, one Hirudinoidea, one Crustacea, and a Dermocystidium sp.) were freshwater and 18 (two Monogenea, seven Digenea, two Cestoidea, two Nematoda, two Acanthocephala, and three Crustacea) were marine. Anadronomous charr were differentiated from nonanadromous charr in fresh water by the presence of marine parasites. Charr in the estuary and lagoon were all considered to be anadromous; however, first-time anadromous charr or smolts were differentiated by the absence of marine parasites and infection with freshwater parasites only. New host records include Lecithaster gibbosus, Zoogonus lasius, Podocotyle angulata, Cryptocotyle lingua (metacercariae), Stephanostomum tenue (metacercariae, adults), Eubothrium crassum, Tetraphyllidea gen. sp. (plerocercoids), Eustrongylides sp. (larvae), Hysterothylacium aduncum (larvae, adults), Corynosoma magdaleni (juveniles), Argulus alosae, and Ergasilus labracis. Zoogonus lasius and Stephanostomum tenue represent new Canadian records, and Chloromyxum truttae and Truttaedacnitis truttae are reported for the first time from New Brunswick. Bulbodacnitis alpinus, previously reported only from the Arctic charr (Salvelinus alpinus), is considered to be a synonym of T. truttae.

Bénéfices à court terme des mouvements anadromes saisonniers pour une population d'omble de fontaine (Salvelinus fontinalis) du Nouveau Québec

1991 ◽  
Vol 48 (11) ◽  
pp. 2212-2222 ◽  
Author(s):  
Jean-François Doyon ◽  
Christiane Hudon ◽  
Roderick Morin ◽  
F. G. Whoriskey Jr.
Keyword(s):  
Water Level ◽  
Egg Size ◽  
Salvelinus Fontinalis ◽  
Condition Factor ◽  
Size At Maturity ◽  
Brook Charr ◽  
Tissue Water Content ◽  
Tissue Water ◽  
Single Population ◽  
Energetic Reserves

This study characterizes the seasonal anadromous movements of a brook charr population and compares its biological and energetic characteristics with charr spending summer in freshwaters. Downstream movements monitored at a counting fence over 3 yr were most intense in spring but occurred until fall and were positively correlated with rapid increases of water level. The timing of movements varied from year to year. Smaller charr were most subject to being swept downstream compared with freshwater residents, and most trout were concentrated near the mouth of the river. These patterns suggest that the downstream movements of charr in this system are passive. Upstream migrants had a higher condition factor and a lower tissue water content than freshwater residents, indicating that downstream movements result in a faster accumulation of energetic reserves during summer. However, the fortuitous character of anadromous migrations as well as the absence of differences in the biological characteristics (growth, size at maturity, fecundity, egg size) suggests that anadromous and resident fish belong to a single population whose yearly migrant component could be randomly determined.

Food Specialization By Individual Trout

1972 ◽  
Vol 29 (11) ◽  
pp. 1615-1624 ◽  
Author(s):  
James E. Bryan ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Potential Prey ◽  
Repeated Observation ◽  
Size Growth ◽  
Salmo Clarki

Analyses of stomach contents showed that the kinds of prey eaten by brook trout (Salvelinus fontinalis), cutthroat trout (Salmo clarki), and rainbow trout (Salmo gairdneri) were seldom distributed at random among the individuals. Repeated observation of food eaten by individuals in a stream and ponds showed that prey types were eaten in proportions which were characteristic for an individual.Specialization occurred on several different kinds of prey. Although the degree of specialization was higher during shorter intervals, the data suggested that some specialization persisted for half a year. There were no striking correlations between degree of specialization and other individual properties such as size, growth rate, weight of food, number of food items, previous specialization, or area of recapture.In addition to the observations on trout in relatively undisturbed habitats, a field experiment was conducted using laboratory-reared rainbow trout held in small ponds. The food of each trout in the experiment was sampled repeatedly. In analysis of variance, interaction among the individuals and kinds of prey eaten showed that food specialization occurred. Both the absolute and relative abundance of potential prey were constant during the experiment.

Mechanisms responsible for the niche shift of brook charr, Salvelinus fontinalis Mitchill, when living sympatrically with creek chub, Semotilus atromaculatus Mitchill

1984 ◽  
Vol 62 (8) ◽  
pp. 1548-1555 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald
Keyword(s):  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Niche Shift ◽  
Intraspecific Aggression ◽  
Brook Charr ◽  
Semotilus Atromaculatus ◽  
High Level ◽  
Gill Raker ◽  
Creek Chub ◽  
Study Laboratory

When brook charr, Salvelinus fontinalis Mitchill, are in allopatry in oligotrophic Québec lakes, they feed largely on macrobenthic invertebrates. However, when brook charr cooccur with creek chub, Semotilus atromaculatus Mitchill, they feed largely on zooplankton. In the present study, laboratory experiments showed that creek chub were more effective than brook charr in searching for hidden, patchily distributed prey. The searching efficiency of an individual chub feeding in a group was improved through social facilitation. In contrast, the high level of intraspecific aggression observed in brook charr prevents the formation of such feeding groups. In the laboratory, brook charr were able to displace creek chub from the food source because of interspecific aggression. Data are presented showing that chub are morphologically better adapted than charr to feed on benthos (subterminal orientation of the mouth and protrusible premaxillae), while the charr are better adapted than chub to feed on zooplankton (gill raker structure). Differences in feeding behaviour, morphology, and relative abundance between these species appear to be important in the observed niche shift of brook charr in nature.

scholarly journals Ecological Observations on Hybrid Populations of European Plethodontid Salamanders, Genus Speleomantes

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 285
Author(s):  
Enrico Lunghi ◽  
Fabio Cianferoni ◽  
Stefano Merilli ◽  
Yahui Zhao ◽  
Raoul Manenti ◽  
...  
Keyword(s):  
Body Condition ◽  
Parental Species ◽  
Stomach Contents ◽  
Trophic Niche ◽  
Natural Hybrid ◽  
Ecological Information ◽  
Total Length ◽  
Plethodontid Salamanders ◽  
The Future ◽  
First Time

Speleomantes are the only plethodontid salamanders present in Europe. Multiple studies have been performed to investigate the trophic niche of the eight Speleomantes species, but none of these studies included hybrid populations. For the first time, we studied the trophic niche of five Speleomantes hybrid populations. Each population was surveyed twice in 2020, and stomach flushing was performed on each captured salamander; stomach flushing is a harmless technique that allows stomach contents to be inspected. We also assessed the potential divergence in size and body condition between natural and introduced hybrids, and their parental species. Previously collected data on Speleomantes were included to increase the robustness of these analyses. In only 33 out of 134 sampled hybrid Speleomantes we recognized 81 items belonging to 11 prey categories. The frequency of empty stomachs was higher in females and individuals from natural hybrid populations, whereas the largest number of prey was consumed by males. We compared the total length and body condition of 685 adult salamanders belonging to three types of hybrids and three parental (sub)species. Three group of salamanders (one hybrid and two parental species) showed significantly larger size, whereas no difference in body condition was observed. This study provided novel ecological information on Speleomantes hybrid populations. We also provided insights into the potential divergence between hybrids and parental species in terms of size and body condition. We discuss our findings, and formulate several hypotheses that should be tested in the future.

Larval sand lance (Ammodytes sp.) in the diet of small juvenile wolffish (Anarhichas spp.): predatory interactions in frontal water masses off western Greenland

2002 ◽  
Vol 59 (11) ◽  
pp. 1759-1767 ◽  
Author(s):  
Peter Munk
Keyword(s):  
Fish Larvae ◽  
Stomach Contents ◽  
Prey Type ◽  
Ontogenetic Changes ◽  
Sand Lance ◽  
Larval Size ◽  
Predatory Behaviour ◽  
Dietary Shift ◽  
Abundance Estimates ◽  
Anarhichas Lupus

The predatory behaviour of two species of juvenile wolffish (Anarhichas lupus and Anarhichas minor) was studied during a field campaign across a frontal area off western Greenland. The study focused on ontogenetic changes in prey-type and -size preference of the wolffish and their predatory impact on a cohabiting population of larval sand lance (Ammodytes sp.). Sampling took place along a cross-shelf transect at latitude 66°20' N, and the analysis is based on stomach contents of assembled wolffish (2–5 cm in length) and abundance estimates of plankton and fish. An ontogenetic change in wolffish prey preference was evident as a dietary shift from copepods and smaller amphipods to larger amphipods and fish larvae. The inclusion of fish larvae in the wolffish diet led to a marked increase in prey biomass, and fish larvae constituted up to 77% of diet biomass in the largest juveniles caught. Wolffish selectively targeted the smaller-sized part of the larval sand lance population; hence, larval vulnerability increased with decreasing size. Comparison between estimated predation rates and abundances of predator and prey indicated larval predation mortalities of up to 5% per day, with mortality peaking in the vicinity of a hydrographic front. Hence, findings suggest substantial predation pressure on larvae, primarily related to larval size and distribution.

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